CN103453538B - A kind of minimum discharge CFBB with three grades of desulphurization systems - Google Patents

Abstract

An ultra-low-emission circulating fluidized bed boiler with a three-stage desulfurization system, the three-stage desulfurization system is a desulfurizer addition system located in the coal yard area in front of the boiler furnace, and an in-furnace desulfurizer delivery system located in the boiler plant area And the deep flue gas desulfurization system located in the tail area of the boiler; the desulfurization agent adding system in front of the furnace includes the desulfurizing agent warehouse in front of the furnace and the desulfurizing agent weighing adding machine in front of the furnace below it, and the desulfurizing agent delivery system in the furnace includes the desulfurizing agent warehouse in the furnace and the desulfurizer conveying feeder in the furnace below it, and the deep flue gas desulfurization system is also equipped with a high-efficiency desulfurizer circulation system and a flue gas supplementary dust removal device; the system of the present invention is simple, low in operation energy consumption, easy to adjust and control, It has high utilization rate, no consumption of water resources, high desulfurization efficiency, and can effectively save space and equipment investment. It is widely applicable to the environmental protection support of new circulating fluidized bed boilers and the environmental protection transformation of existing circulating fluidized bed boilers.

Description

An ultra-low emission circulating fluidized bed boiler with a three-stage desulfurization system

technical field

The invention relates to the technical field of circulating fluidized bed boilers, in particular to an ultra-low emission circulating fluidized bed boiler with a three-stage desulfurization system.

Background technique

my country is the world's major coal producer and consumer, and also a country that uses coal as its primary energy source. The flue gas produced by coal combustion contains a large amount of pollutants such as sulfur dioxide, nitrogen oxides and heavy metals, causing serious environmental pollution. According to the 2012 Bulletin on the State of the Environment in China, the national emission of sulfur dioxide in waste gas was as high as 21.176 million tons in 2012, and thermal power generation has always been one of the main sources of sulfur dioxide emission.

In order to strengthen environmental protection and achieve the goal of energy conservation and emission reduction, the "Emission Standard of Air Pollutants for Thermal Power Plants" (GB13223-2011) stipulates that the existing thermal power boilers located in Guangxi Zhuang Autonomous Region, Chongqing City, Sichuan Province and Guizhou Province shall implement 400mg/m ³ , new thermal power boilers implement a sulfur dioxide emission limit of 200mg/ ^m3 , existing thermal power boilers in other non-key areas implement a sulfur dioxide emission limit of 200mg/ ^m3 , and newly built thermal power boilers implement a sulfur dioxide emission limit of 100mg/m3. m ³ sulfur dioxide emission limit, for thermal power boilers in key areas, the sulfur dioxide emission limit is only 50mg/m ³ .

As we all know, my country is the country with the largest installed capacity and number of circulating fluidized bed boilers and the highest unit parameters. Traditional circulating fluidized bed boilers mainly rely on desulfurization in the furnace. After the latest environmental protection standards are issued, most of these boilers need technical transformation. At present, the domestic desulfurization technology is dominated by limestone-gypsum wet desulfurization process. The limestone-gypsum wet desulfurization process needs to consume a lot of water resources, and the gypsum waste generated is not easy to comprehensively utilize. In addition, the operating cost is extremely high. If the limestone-gypsum wet method is used in circulating fluidized bed boilers, the cost is extremely high. The thermal power plants that use circulating fluidized bed boilers urgently need a kind of low application conditions, low water consumption and high efficiency. The advanced desulfurization technology is used for the transformation of new units and existing units.

Chinese invention patent application 200810138603.2 discloses a flue gas calcium injection desulfurization process in a circulating fluidized bed boiler, sending CaO powder into a cyclone separator with a temperature of ≤950°C or a horizontal flue behind the first steam superheater or/ And the desulfurization reaction occurs in the tail flue. Since there is only one-stage desulfurization system, this method obviously cannot meet the requirements of the latest environmental protection standards. In addition, the cost of CaO is much higher than that of limestone. Due to the finer particle size of CaO, short residence time and low utilization rate, System running costs are high.

Chinese patent application 02135540.1 discloses a circulating fluidized bed boiler composite desulfurization process. In this process, limestone particles are added to the circulating fluidized bed boiler, desulfurization in the furnace is carried out first, and then humidification and desulfurization outside the furnace are carried out in the humidification tower, finally forming a composite desulfurization process of combustion desulfurization in the furnace and humidification and desulfurization at the tail. This process improves the desulfurization efficiency of the circulating fluidized bed boiler to a certain extent, but it brings many new problems due to the need to install a humidifying tower. First, due to the need to utilize unreacted limestone, the position of the humidification tower must be set before the dust collector, which is difficult for the existing circulating fluidized bed boiler; second, the humidification process itself consumes a lot of water , the flue gas with water will affect the operation of the dust collector, causing new problems such as dust exceeding the standard and short service life of the equipment; third, the desulfurization efficiency of the tail humidification desulfurization itself is not high, and even the composite desulfurization process cannot meet the latest requirements. Fourth, the quality of the fly ash after adding water decreases and cannot be comprehensively utilized.

Chinese utility model patent 2009200003396.X discloses a new coal-fired boiler desulfurization device composed of three-stage desulfurization process. The device is composed of a circulating fluidized bed boiler, a water quenching activator and a charged coagulator in series, and performs desulfurization by combustion in the circulating fluidized bed boiler, desulfurization by water quenching activation of the desulfurizer outside the furnace, and charge activation desulfurization outside the furnace, respectively. The water quenching activator used in this process consumes a lot of water, the charged coagulator consumes a lot of electricity, and the economy is poor. In addition, the water quenching activation and charged coagulation process itself will affect the activity of fly ash. The fly ash after adding water cannot be used for comprehensive utilization with high added value, and the use value is greatly reduced. There are no public reports on the use of this technology.

Chinese invention patent application 200910112434.X discloses a flue gas desulfurization synergistic device and a desulfurization synergistic method after a circulating fluidized bed boiler. The method device is provided with a reactor, a dust remover, an absorbent auxiliary adding system, a desulfurization ash recycling system and a process water system. The boiler flue gas first enters the reactor and is pre-mixed with circulating desulfurization ash. The limestone is calcined in the furnace to form quicklime powder. The fly ash mixed with quicklime powder enters the downstream reactor with the flue gas. After spraying water to cool down, the quicklime is directly reacted in the reactor to form Slaked lime desulfurization reaction. This method also requires a large amount of water spraying to reduce the flue gas temperature, and has strict requirements on the process control parameters, otherwise the desulfurization efficiency cannot be guaranteed, the water consumption is high, the desulfurization efficiency is low, the fly ash cannot be comprehensively utilized, and the scope of application is limited. In addition, if the system is simply used, it still cannot meet the requirements of the latest environmental standards.

Chinese invention patent application 201110330529.6 discloses a three-stage desulfurization device for a circulating fluidized bed boiler. The device desulfurizes flue gas in the boiler, cyclone separator and semi-dry desulfurizer. The flue outlet pipe of the device adopts a bifurcated structure, one of which is tangentially connected to the higher part of the semi-dry desulfurizer. , The other road is tangentially connected to the lower part of the semi-dry desulfurizer. Since slaked lime is mainly used as the desulfurizer and still needs to be sprayed with water, the water consumption is high and the desulfurization efficiency is low. The fly ash cannot be comprehensively utilized and the scope of application is limited. The requirements of the latest environmental standards.

Obviously, the existing technology has low desulfurization efficiency, high operating costs, and poor quality of fly ash that cannot be comprehensively utilized. In addition, the transformation workload is large, water consumption is high, and the scope of application is small. It is not suitable for regions and water-scarce regions. The existing circulating fluidized bed boiler urgently needs to develop a flue gas pollutant removal process with high desulfurization efficiency, low operating cost, no water consumption, and small renovation project to meet the requirements of the latest national environmental protection standards.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the object of the present invention is to provide an ultra-low emission circulating fluidized bed boiler with a three-stage desulfurization system. The system of the present invention is simple, low energy consumption in operation, easy to adjust and control, It has high utilization rate, no consumption of water resources, high desulfurization efficiency, and can effectively save space and equipment investment. It is widely applicable to the environmental protection support of new circulating fluidized bed boilers and the environmental protection transformation of existing circulating fluidized bed boilers.

In order to achieve the above object, the present invention adopts the following technical solutions:

An ultra-low emission circulating fluidized bed boiler with a three-stage desulfurization system, including a three-stage desulfurization system. In-furnace desulfurizer delivery system B in the plant area and deep flue gas desulfurization system C located in the boiler tail area; the furnace desulfurizer addition system A includes furnace desulfurizer bin A1 and the furnace desulfurizer weighing system below it Adding machine A2, the granular desulfurizer is added to the raw coal conveyor belt 2 between the raw coal 1 of the coal yard and the raw coal crushing and screening system 3 through the desulfurizing agent bin A1 in front of the furnace by the desulfurizing agent weighing type adding machine A2 in front of the furnace; The internal desulfurizing agent conveying system B includes the furnace desulfurizing agent bin B1 and the furnace desulfurizing agent conveying feeder B2 below it. The feed pipe 15 is sent to the furnace dense-phase zone 7 for desulfurization; the deep flue gas desulfurization system C is also equipped with a high-efficiency desulfurizer circulation system C1 and a flue gas supplementary dust removal device C2, and the flue gas after dust removal is cooled by the exhaust gas temperature After the device 24 is cooled to close to the saturation temperature, it is sent to the deep flue gas desulfurization system C for deep removal of sulfur dioxide in the flue gas, and then it is sent to the chimney 26 by the induced draft fan 25 after being treated by the flue gas supplementary dust removal device C2. The high-efficiency desulfurization The desulfurizer is recycled through the high-efficiency desulfurizer circulation system C1.

The amount of desulfurizing agent used in the pre-furnace desulfurizing agent addition system A, in-furnace desulfurizing agent delivery system B and deep flue gas desulfurizing system C is independently adjusted according to the difference in coal type and flue gas sulfur dioxide concentration.

The granular desulfurizer used in the furnace front desulfurizer addition system A is limestone, calcium carbide slag, slaked lime or other calcium-containing substances, with a particle size of 1-20 mm and a median diameter of 1-5 mm; the furnace desulfurizer The powdery desulfurizer used in conveying system B is limestone, calcium carbide slag, slaked lime or other calcium-containing substances, with a particle size of 0.1-1.5 mm and a median diameter of 0.2-0.8 mm; the deep flue gas desulfurization system C uses High-efficiency desulfurizers are limestone, calcium carbide slag, slaked lime or other calcium-containing substances, which use chemical reactions for desulfurization; or high-efficiency desulfurizers are activated carbon, activated coke, and activated semi-coke media with internal pore structures and adsorption capabilities, which use adsorption reactions for desulfurization .

Sodium chloride or potassium chloride desulfurization enhancer is added to the granular desulfurizer used in the furnace desulfurizer addition system A and the powdery desulfurizer used in the furnace desulfurizer delivery system B, and the added amount is the total amount of desulfurizer added. 1% to 15% of the amount.

The desulfurizing agent conveying system B in the furnace adopts pneumatic conveying, and the conveying gas source of the desulfurizing agent conveying feeder B2 in the furnace is compressed air or high-pressure fluidized air.

The circulating fluidized bed boiler includes a raw coal conveying belt 2 sequentially connected to the raw coal 1 of the coal yard, a raw coal crushing and screening system 3, a furnace coal conveying belt 4, a furnace coal bin 5, a coal feeding belt 6 and a furnace dense phase zone 7 , the bottom of the furnace dense-phase area 7 is connected with the slag cooler 9 through the slag drop pipe 8, and the slag cooler 9 is connected with the desulfurization ash bin 27 in the furnace. 10 is communicated with the separator 12 through the separator inlet flue 11, the separator inlet flue 11 is provided with a reducing agent nozzle 20, and the lower part of the separator 12 is connected with the furnace closet through the standpipe 13, the return valve 14 and the return pipe 15. The phase zone 7 is connected, and the upper part of the separator 12 is connected with the dust collector 23 through the tail flue 21. The tail flue 21 is provided with a tail flue heating surface 22, and the lower part of the return valve 14 is provided with a circulating ash discharge pipe 16, and the circulating ash is discharged. The pipe 16 communicates with the circulating ash cooler 17, and the circulating ash cooler 17 is provided with a circulating ash cooler heating surface 18, and the circulating ash cooler 17 and the circulating ash bin 19 communicate with the desulfurization ash bin 27 in the furnace in turn, and the dust collector 23 The upper part is connected with the exhaust gas temperature desuperheater 24, the exhaust gas temperature desuperheater 24 is connected with the deep flue gas desulfurization system C, the lower part of the deep flue gas desulfurization system C is connected with the desulfurization ash bin 28 outside the furnace, and the lower part of the dust collector 23 is connected with the furnace The inner desulfurization ash bin 27 is connected.

The denitrification reducing agent sprayed into the reducing agent nozzle 20 is urea aqueous solution, liquid ammonia or ammonia water.

The cooling medium in the exhaust gas temperature desuperheater 24 is desalted water.

The combustion temperature of the circulating fluidized bed boiler is 850-950°C.

Compared with the prior art, the present invention has the following advantages:

1. The system is simple, the transformation workload is small, the space occupation is small and the equipment investment is low, and it can be applied to the transformation and new construction of circulating fluidized bed boilers of different capacity levels;

2. The three-stage desulfurization works together, the desulfurization efficiency is high, and the emission concentration of sulfur dioxide in the flue gas can be stably lower than 50mg/m ³ ;

3. No water consumption, low operating energy consumption, especially suitable for water-scarce areas and pit mouth areas;

4. The desulfurization process does not affect the comprehensive utilization of ash;

5. Convenient operation and control, high utilization rate of desulfurizer, good regulation performance.

The most notable feature of the present invention is that the three-stage desulfurization system works simultaneously to ensure the final denitrification efficiency. For example, the latest standards often require the desulfurization efficiency to be above 98%. However, it is not easy to simply use the inside of the furnace, the outside of the furnace, or the inside and outside of the furnace. However, if the front of the furnace + inside the furnace + outside the furnace are used, the combination of the three reduces the need for each level and the system can also be simplified.

Description of drawings

Accompanying drawing is the application flowchart of the present invention.

detailed description

The present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, an ultra-low emission circulating fluidized bed boiler with a three-stage desulfurization system according to the present invention includes a raw coal conveying belt 2 sequentially connected to the raw coal 1 of the coal yard, a raw coal crushing and screening system 3, and a furnace coal Conveyor belt 4, furnace coal bunker 5, coal feeding belt 6 and furnace dense-phase area 7, the bottom of furnace dense-phase area 7 is connected through slag falling pipe 8 and slag cooler 9, slag cooler 9 and furnace desulfurization ash bin 27 connected, above the furnace dense-phase zone 7 is the furnace dilute-phase zone 10, and above the furnace dilute-phase zone 10 is connected to the separator 12 through the separator inlet flue 11, and the separator inlet flue 11 is provided with a reducing agent spout 20, in the cycle On the basis of low-nitrogen combustion of fluidized bed boilers, the emission concentration of nitrogen oxides is further reduced. The lower part of the separator 12 communicates with the dense phase zone 7 of the furnace through the standpipe 13, the return valve 14 and the return pipe 15, and the upper part of the separator 12 communicates with the dust collector 23 through the tail flue 21, and the tail flue 21 is provided with a tail flue Circulating ash discharge pipe 16 is provided at the lower part of the return valve 14, and the circulating ash discharge pipe 16 communicates with the circulating ash cooler 17. The circulating ash cooler 17 is provided with a circulating ash cooler heating surface 18, and the circulating ash cooling The device 17 and the circulating ash bin 19 are sequentially connected with the desulfurization ash bin 27 in the furnace. When a large amount of desulfurization is added, the circulating ash cooler 17 can reduce the ash concentration in the furnace, adjust the operating conditions of the boiler, and slow down wear. The top of the dust collector 23 is connected to the exhaust gas temperature desuperheater 24, the exhaust gas temperature desuperheater 24 is connected to the deep flue gas desulfurization system C, the bottom of the deep flue gas desulfurization system C is connected to the desulfurization ash bin 28 outside the furnace, and the dust collector 23 The bottom communicates with the desulfurization ash bin 27 in the furnace. The three-stage desulfurization system is respectively a furnace desulfurization agent addition system A located in the coal yard area in front of the boiler furnace, an in-furnace desulfurizer delivery system B located in the boiler plant area, and a deep flue gas desulfurization system C located in the boiler tail area; The furnace desulfurizer adding system A includes the furnace desulfurizer bin A1 and the furnace desulfurizer weight adding machine A2 below it, and the granular desulfurizer is added by the furnace desulfurizer weight through the furnace desulfurizer bin A1 The machine A2 is added to the raw coal conveying belt 2 between the raw coal 1 of the coal yard and the raw coal crushing and screening system 3; the desulfurizing agent conveying system B in the furnace includes the desulfurizing agent bin B1 in the furnace and the desulfurizing agent conveying feed material in the furnace below it Machine B2, the powdery desulfurizer is sent to the furnace dense-phase zone 7 through the furnace desulfurizer bin B1 by the furnace desulfurizer feeder B2 from the return pipe 15 for desulfurization; the deep flue gas desulfurization system C is also set There is a high-efficiency desulfurizer circulation system C1 and a flue gas supplementary dust removal device C2. The flue gas after dust removal is cooled to a temperature close to the saturation temperature by the exhaust gas temperature desuperheater 24 and then sent to the deep flue gas desulfurization system C for deep removal of sulfur dioxide in the flue gas. After being treated by the flue gas supplementary dedusting device C2, it is sent to the chimney 26 by the induced draft fan 25 to be discharged, and the high-efficiency desulfurizer is recycled through the high-efficiency desulfurizer circulation system C1.

In the present invention, the amount of desulfurizing agent used in the pre-furnace desulfurizing agent addition system A, in-furnace desulfurizing agent delivery system B, and deep flue gas desulfurization system C is independently adjusted according to the difference in coal type and flue gas sulfur dioxide concentration. Together with the furnace desulfurization agent delivery system B, it can remove 50% to 90% of the sulfur dioxide produced by combustion, and the remaining part is removed by the deep flue gas desulfurization system C. The final sulfur dioxide emission concentration can be as low as below 50mg/m ³ .

As a preferred embodiment of the present invention, in order to improve the desulfurization efficiency, the granular desulfurizer used in the furnace pre-furnace desulfurizer addition system A is limestone, carbide slag, slaked lime or other calcium-containing substances, and its particle size is 1-20mm. The bit diameter is 1-5mm; the powdery desulfurizer used in the furnace desulfurizer delivery system B is limestone, carbide slag, slaked lime or other calcium-containing substances, the particle size is 0.1-1.5mm, and the median diameter is 0.2- 0.8mm; the high-efficiency desulfurization agent used in the deep flue gas desulfurization system C is limestone, calcium carbide slag, slaked lime or other calcium-containing substances, and desulfurization is carried out by chemical reaction; or the high-efficiency desulfurization agent is activated carbon, activated coke, and activated semi-coke. The medium with internal pore structure and adsorption capacity uses adsorption reaction for desulfurization.

Especially for the high combustion temperature of some circulating fluidized bed boilers in China, the granular desulfurizer used in the furnace desulfurizer addition system A and the powder desulfurizer used in the furnace desulfurizer delivery system B are added with chlorinated The sodium or potassium chloride salt desulfurization enhancer is added in an amount of 1% to 15% of the total amount of desulfurization agent added. Reduce the decomposition rate of calcium sulfate during combustion and increase the desulfurization efficiency. Therefore, the combustion temperature of the circulating fluidized bed boiler is 850-950 °C.

As a preferred embodiment of the present invention, the in-furnace desulfurizing agent conveying system B adopts pneumatic conveying, and the conveying gas source of the in-furnace desulfurizing agent conveying feeder B2 is compressed air or high-pressure fluidized air.

As a preferred embodiment of the present invention, the denitration reducing agent sprayed into the reducing agent nozzle 20 is urea aqueous solution, liquid ammonia or ammonia water.

As a preferred embodiment of the present invention, the cooling medium in the exhaust gas temperature desuperheater 24 is demineralized water.

Since the desulfurization and desulfurization ash in the furnace generated by the desulfurization agent addition system A in front of the furnace and the desulfurization agent delivery system B in the furnace are uniformly sent to the desulfurization ash bin 27 in the furnace, this part of the ash has high activity and can be used for cement, bricks, etc. The production has higher utilization value. The out-of-furnace desulfurization ash generated by the deep flue gas desulfurization system C is sent to the out-of-furnace desulfurization ash bin 28. Since it contains active and unstable substances such as calcium sulfite, this part of ash can be used for roadbeds and landfills in mining areas.

The working principle of the present invention is: the raw coal 1 of the coal yard enters the raw coal crushing and screening system 3 through the raw coal conveying belt 2, the desulfurizing agent adding system A before the furnace is used as the first-stage desulfurizing system, and the granular desulfurizing agent used by the desulfurizing agent adding system A before the furnace The desulfurizer is stored in the desulfurizer warehouse A1 in front of the furnace, and is added to the raw coal conveyor belt 2 through the desulfurizer weighing type adding machine A2 in front of the furnace, and the granular desulfurizer is mixed with the raw coal under the crushing and screening action of the raw coal crushing and screening system 3 Uniformly become the furnace coal that contains the granular desulfurizer, and finally sent to the furnace coal bunker 5 by the furnace coal conveyor belt 4 for subsequent use. The coal entering the furnace enters the dense phase zone 7 of the furnace through the coal feeding belt 6 to fully burn and complete the desulfurization during combustion. The powdery desulfurizer used in the furnace desulfurizer delivery system B is fed by the desulfurizer in the furnace through the desulfurizer bin B1. The machine B2 is sent from the return pipe 15 to the dense-phase zone 7 of the furnace for desulfurization. The ash and slag enter the slag cooler 9 through the slag falling pipe 8 to be cooled and then sent to the desulfurization ash bin 27 in the furnace. The dust-laden flue gas produced by combustion enters the separator 12 through the furnace dilute phase zone 10 and the separator inlet flue 11 respectively, and most of the dust is separated and sent back to the furnace through the standpipe 13, the return valve 14 and the return pipe 15 In the dense-phase area 7, the flue gas passes through the tail flue 21, is cooled by the heating surface 22 of the tail flue, and then enters the dust collector 23. The reducing agent nozzle 20 of the inlet flue 11 of the separator is used for spraying the denitration reducing agent. The circulating ash enters the circulating ash cooler 17 through the circulating ash discharge pipe 16 at the lower part of the return valve 14. The circulating ash is cooled by the heating surface 18 of the circulating ash cooler and then sent to the desulfurization ash bin 27 in the furnace. The flue gas after dedusting in the dust collector 23 is cooled by the exhaust gas temperature desuperheater 24 to close to the saturation temperature, and then sent to the deep flue gas desulfurization system C to realize the deep removal of sulfur dioxide in the flue gas. The high-efficiency desulfurizer passes through the high-efficiency desulfurizer circulation system C1 can realize recycling, and the ash after deep desulfurization is sent to the desulfurization ash bin 28 outside the furnace. The deep flue gas desulfurization system C itself is also equipped with a supplementary flue gas dedusting device C2, and the flue gas treated by it is finally sent to the chimney 26 by the induced draft fan 25 for discharge.

Embodiment one

As shown in Figure 1, it is a newly built 300MW circulating fluidized bed boiler with a three-stage desulfurization system. The combustion temperature of the boiler is 900°C, and the desulfurization agent addition system A in front of the furnace uses limestone particles with a median diameter of 3mm. District 7. The desulfurizer conveying system B in the furnace conveys limestone powder with a median diameter of 0.5 mm from the return pipe 15 to the dense-phase zone 7 of the furnace. The desulfurized flue gas in the furnace is cooled to 100°C by the exhaust gas temperature desuperheater 24, and then sent to the deep flue gas desulfurization system C for deep desulfurization. The desulfurization agent used in the deep flue gas desulfurization system C is slaked lime. The reducing agent nozzle 20 sprays the aqueous urea solution to the inlet flue 11 of the separator to further reduce the emission concentration of nitrogen oxides on the basis of the low-nitrogen combustion of the circulating fluidized bed boiler.

Desulfurizer addition system A before the furnace, desulfurizer delivery system B in the furnace, and deep flue gas desulfurization system C respectively remove 40%, 30% and 25% of the sulfur dioxide generated by combustion. During operation, the desulfurizer delivery system B in the furnace is mainly adjusted. and deep flue gas desulfurization system C to control the final sulfur dioxide emission concentration below 50mg/m ³

Embodiment two

A newly built 135MW circulating fluidized bed boiler with a three-stage desulfurization system. The combustion temperature of the boiler is 935°C. The desulfurization agent addition system A in front of the furnace uses limestone particles with a median diameter of 2mm, and the desulfurizer delivery system B in the furnace uses limestone powder with a median diameter of 0.3mm. A desulfurizer is also added to improve the desulfurization efficiency. The total amount of 3% sodium chloride desulfurization enhancer reduces the decomposition rate of calcium sulfate during combustion and improves the desulfurization efficiency.

Embodiment Three

A remodeled 200MW circulating fluidized bed boiler. The boiler was originally equipped with a desulfurization agent delivery system B in the furnace. A pre-furnace desulfurization agent addition system A and a deep flue gas desulfurization system C were added to the boiler. Through three-stage desulfurization The final sulfur dioxide emission concentration of the boiler is lower than 100mg/m ³ .

Embodiment four

A newly built 600MW grade circulating fluidized bed boiler with a three-stage desulfurization system. The combustion temperature of the boiler is 880°C. The desulfurizer addition system A in front of the furnace uses limestone particles with a median diameter of 3mm, and the desulfurizer delivery system B in the furnace uses limestone powder with a median diameter of 0.4mm. The deep flue gas desulfurization system C uses the active coke adsorption method for deep desulfurization, the saturated activated coke can be discharged for regeneration, and the regenerated active coke and new activated coke are supplemented by the high-efficiency desulfurizer circulation system C1.

Claims (9)

1. the minimum discharge CFBB with three grades of desulphurization systems, it is characterized in that: comprise three grades of desulphurization systems, before described three grades of desulphurization systems are respectively and are positioned at Boiler Furnace coal yard region stokehole desulfuration agent add-on system (A), be positioned at the desulfuration in furnace agent induction system (B) in boiler factory building region and be positioned at the degree of depth flue gas desulphurization system (C) in boiler tail region; Described stokehole desulfuration agent add-on system (A) comprises stokehole desulfuration agent storehouse (A1) and stokehole desulfuration agent Weighing type adding machine (A2) below it, and graininess desulfurizing agent adds on the raw coal belt conveyor (2) between coal yard raw coal (1) and raw coal pulverizing-screening system (3) by stokehole desulfuration agent storehouse (A1) by stokehole desulfuration agent Weighing type adding machine (A2); Described desulfuration in furnace agent induction system (B) comprises desulfuration in furnace agent storehouse (B1) and conveying batcher of the desulfuration in furnace agent below it (B2), and desulfurizer powder carries batcher (B2) to carry out desulfurization from feed back pipe (15) feeding burner hearth emulsion zone (7) by desulfuration in furnace agent storehouse (B1) by desulfuration in furnace agent; Described degree of depth flue gas desulphurization system (C) is also provided with the efficient desulfurizing agent circulatory system (C1) and flue gas supplements dust arrester (C2), flue gas after dedusting is cooled to the deep removal close to sending into degree of depth flue gas desulphurization system (C) after saturation temperature and carry out sulfur dioxide in flue gas by exhaust gas temperature attemperator (24), with after to supplement through flue gas and send into chimney (26) by air-introduced machine (25) after dust arrester (C2) process and discharge, described efficient desulfurizing agent is recycled by the efficient desulfurizing agent circulatory system (C1).

2. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 1, is characterized in that: the respective desulfurizing agent use amount of described stokehole desulfuration agent add-on system (A), desulfuration in furnace agent induction system (B) and degree of depth flue gas desulphurization system (C) independently regulates according to the difference of coal and SO 2 from fume concentration.

3. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 1, it is characterized in that: the graininess desulfurizing agent that described stokehole desulfuration agent add-on system (A) uses is lime stone, carbide slag, calcium hydroxide or other calcareous materials, its particle diameter is 1 ~ 20mm, and meso-position radius is 1 ~ 5mm; The desulfurizer powder that described desulfuration in furnace agent induction system (B) uses is lime stone, carbide slag, calcium hydroxide or other calcareous materials, and its particle diameter is 0.1 ~ 1.5mm, and meso-position radius is 0.2 ~ 0.8mm; The efficient desulfurizing agent that described degree of depth flue gas desulphurization system (C) uses is lime stone, carbide slag, calcium hydroxide or other calcareous materials, utilizes chemical reaction to carry out desulfurization; Or efficient desulfurizing agent be active carbon, activated coke, active carbocoal have the medium of internal pore structure and adsorption capacity, utilizes adsorption reaction to carry out desulfurization.

4. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 3, it is characterized in that: be added with sodium chloride or potassium chloride desulfurization hardening agent in the graininess desulfurizing agent that described stokehole desulfuration agent add-on system (A) uses and the desulfurizer powder that desulfuration in furnace agent induction system (B) uses, addition is that desulfurizing agent adds 1% ~ 15% of total amount.

5. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 1, it is characterized in that: described desulfuration in furnace agent induction system (B) adopts Geldart-D particle, the conveying source of the gas of desulfuration in furnace agent conveying batcher (B2) is compressed air or hp fluid air.

6. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 1, it is characterized in that: described CFBB comprises the raw coal belt conveyor (2) be connected successively with coal yard raw coal (1), raw coal pulverizing-screening system (3), as-fired coal belt conveyor (4), stove coal bunker (5), coal supply belt (6) and burner hearth emulsion zone (7), burner hearth emulsion zone (7) below is communicated with slag cooler (9) by slag dropping tube (8), slag cooler (9) is communicated with desulfuration in furnace cinder tank (27), burner hearth emulsion zone (7) top is burner hearth dilute-phase zone (10), burner hearth dilute-phase zone (10) top is communicated with separator (12) by separator inlet flue (11), separator inlet flue (11) is provided with reducing agent spout (20), separator (12) below is by standpipe (13), material returning valve (14) is communicated with burner hearth emulsion zone (7) with feed back pipe (15), separator (12) top is communicated with deduster (23) by back-end ductwork (21), back-end ductwork heating surface (22) is provided with in back-end ductwork (21), material returning valve (14) bottom is provided with circulating ash delivery pipe (16), circulating ash delivery pipe (16) communicates with circulating ash cooler (17), circulating ash cooler heating surface (18) is provided with in circulating ash cooler (17), circulating ash cooler (17) is communicated with desulfuration in furnace cinder tank (27) successively with circulation ash silo (19), deduster (23) top is connected with exhaust gas temperature attemperator (24), exhaust gas temperature attemperator (24) is connected with degree of depth flue gas desulphurization system (C), degree of depth flue gas desulphurization system (C) below is communicated with external desulfurzation cinder tank (28), deduster (23) below is communicated with desulfuration in furnace cinder tank (27).

7. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 6, is characterized in that: the denitrification reducing agent that described reducing agent spout (20) sprays into is aqueous solution of urea, liquefied ammonia or ammoniacal liquor.

8. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 6, is characterized in that: the cooling medium in described exhaust gas temperature attemperator (24) is demineralized water.

9. a kind of minimum discharge CFBB with three grades of desulphurization systems according to claim 6, is characterized in that: the ignition temperature of described CFBB is 850 ~ 950 DEG C.